JP2003270808A - Undercoat layer coating liquid for electrophotographic photoreceptor, method for preparing the same, electrophotographic photoreceptor and image forming apparatus with the photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an undercoat layer coating liquid for an electrophotographic photoreceptor having good dispersibility and excellent in aging stability and suitability to coating on an electrically conductive substrate and to provide a method for preparing the coating liquid. <P>SOLUTION: In the method for preparing the undercoat layer coating liquid for an electrophotographic photoreceptor in which at least metal oxide particles and a bonding resin are dispersed, a mixed solvent consisting of a cyclic ketone solvent which dissolves the bonding resin and a side chain ketone solvent is added from the initial stage of a dispersing step and the metal oxide is wet- pulverized to prepare the undercoat layer coating liquid. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating liquid for an electrophotographic photosensitive member, and more specifically, a coating liquid containing an inorganic oxide free from the generation of undispersed substances in the dispersion step during the preparation of the coating liquid. For electrophotographic photoreceptors that do not cause sedimentation due to aggregation peculiar to the liquid, change little as a paint such as viscosity increase even during long-term storage, and have excellent stability as a coating liquid, and thus high yield and excellent productivity. The present invention relates to an undercoat layer coating solution and a method for producing the same. The present invention also relates to an electrophotographic photoconductor, and further to a photoconductor which is free from image defects such as white spots and black spots and is stable in electrophotographic characteristics, and an image forming apparatus including the same.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic photosensitive member,
Those having a photosensitive layer containing an inorganic photoconductor as a main component such as selenium, cadmium sulfide, zinc oxide, and silicon have been widely known. However, they are sensitive, heat stable, moisture resistant,
Durability and the like are not always satisfactory, and particularly selenium and cadmium sulfide are restricted in production and handling due to their toxicity.

On the other hand, an electrophotographic photosensitive member having a photosensitive layer containing an organic photoconductive compound as a main component is relatively easy to manufacture, inexpensive, easy to handle, and generally selenium photosensitive. It has many advantages such as superior thermal stability to the body, and has received much attention in recent years.

As such an organic photoconductive compound,
Poly-N-vinylcarbazole is well known, and an electrophotographic photosensitive material having a photosensitive layer containing as a main component a charge transfer complex formed from this and a Lewis acid such as 2,4,7-trinitro-9-fluorenone. The body is special Japanese Sho 50-10496
It is described in Japanese Patent Publication No. However, this photoreceptor was not always satisfactory in sensitivity, film-forming property, and durability.

On the other hand, charge-transporting substances typified by triphenylamines, stilbenes and hydrazones,
There has been proposed an electrophotographic photoreceptor containing a low molecular weight organic photoconductive compound in combination with a charge generating substance such as phthalocyanine and an azo pigment. By combining these with an appropriate binder resin, and further combining a compound having a high charge generating ability and a compound having a high charge transporting ability, for example, as a laminated type photoreceptor, a compound having a sensitivity close to that of an inorganic photoreceptor such as selenium also appears. is doing. As a result, in the field of copying machines, printers, etc., photoconductors containing such an organic photoconductive compound as a main component have made great progress.

The laminated or dispersed function-separated type photoreceptor in which the charge generating function and the charge transporting function are shared by different substances has a wide selection range of each material, and the charging characteristics, sensitivity and durability are large. It has an advantage that an electrophotographic photosensitive member having arbitrary characteristics in terms of electrophotographic characteristics can be prepared relatively easily.

When such a function-separated type photoreceptor is applied to an electrophotographic process, dark decay is large due to generally poor charging characteristics and charge retention, and the above characteristics are largely deteriorated due to repetition. However, the residual potential is remarkably increased, and there is a defect that density unevenness, fog, etc. occur on the image. In order to improve the electrical characteristics of such a photoreceptor, it is effective to provide an undercoat layer between the conductive substrate and the photosensitive layer. Generally, the purpose of providing the undercoat layer is to improve surface defects of the conductive substrate, improve adhesion between the photosensitive layer and the conductive substrate, improve coatability of the photosensitive layer, and charge from the conductive substrate to the photosensitive layer. Examples include suppression of injection.

As the undercoating layer which has been proposed in the past, an electrically insulating polymer film has been generally used. For example, JP-A-58-98739 and JP-A-60-66258 disclose a nylon resin undercoat layer, and JP-A-58-105155 discloses a polyvinyl alcohol resin undercoat layer. There is. However, these resin single-layer undercoat layers have excellent adhesiveness, but have the drawback that the residual potential increases due to repeated electric resistance due to high electric resistance, and the background stain occurs on the image.

A film in which insulating inorganic compound particles such as SiO ₂ are contained in a binder resin is also used as the undercoat layer. This undercoat layer is also the undercoat of the above-mentioned resin single layer. It had the same drawbacks as the layers.

Therefore, a subbing layer in which particles having an appropriate electric conductivity are contained in a binder resin in order to control the electric resistance of the subbing layer is proposed today. For example, in JP-A-58-58556, an undercoat layer in which an oxide of aluminum or tin is dispersed in a resin is disclosed in JP-A-58-93.
No. 06 and JP-A-60-97363 disclose an undercoat layer in which conductive particles are dispersed in a resin, and JP-A-5-97363.
9-84257 and JP-A-60-32054 disclose an undercoat layer in which TiO ₂ powder and SnO ₂ powder are dispersed in a resin.

However, in a coating liquid for an undercoat layer in which particles having a proper electric conductivity as described above, particularly metal oxide particles, which are necessary for coating a conductive support, are dispersed in an organic layer. Although the step of stably and completely dispersing in a solvent or the like is required, in reality, the particles cannot be completely dispersed and an undispersed substance remains at the end of the wet pulverization step. In addition, the agglomerates of the particles (soft agglomeration due to a weak bond due to van der Waals force between particles) increase in the liquid over time, resulting in a coating defect caused by coating it, resulting in black They had the problem of image defects such as spots and spots.

In order to solve this, measures have been taken by improving the dispersion method of the coating liquid for the undercoat layer. Japanese Unexamined Patent Publication No. 10-254150 proposes an undercoat layer coating liquid containing inorganic particles and a binder resin prepared by dissolving a binder resin in a slurry of dispersed inorganic particles. Japanese Patent Laid-Open No. 2000-1121
No. 64, the dispersibility is obtained by washing and dispersing the metal oxide particles with an organic solvent in an undercoat layer coating liquid having a metal oxide surface-treated with an organic compound and a binder resin,
Alternatively, there has been proposed a method of improving the coating property when the undercoat layer is coated. Further, in JP-A-8-166678, in a method for producing an undercoating coating liquid for an electrophotographic photosensitive member, in which titanium oxide is dispersed in at least a binder resin-dissolved organic solvent, the coating liquid has a solid content higher than the final concentration. A primary dispersion step of dispersing the total amount of titanium oxide to be dispersed in an organic solvent in which the binder resin is dissolved in an amount of 30% by weight or less based on the total amount of the binder resin, and the binder resin was dissolved in the primary dispersion coating liquid. A method for producing an undercoat coating liquid for an electrophotographic photoreceptor, which comprises a secondary dispersion step of further dispersing after adding an organic solvent to obtain a final solid content concentration, and a bottom formed from the undercoat coating liquid. Provided is an electrophotographic photosensitive member having a pulling layer.

However, Japanese Patent Laid-Open No. 10-254150
When the resin is added after dispersing the inorganic particles as described in JP-A No. 2004-242242, the adsorption of the resin to the inorganic particles may be insufficient and the inorganic particles may be in direct contact with the charge generating substance. There is a high possibility that black spots will frequently occur in a trim image when a reversal development type electrophotographic image forming apparatus is used because of a high degree of small charge reduction. JP 2000-1
In the invention described in Japanese Patent No. 12164, it is attempted to prevent cissing of the coating film by removing the lipophilic substance adsorbed on the surface of the metal oxide particles by washing the dispersed metal oxide particles with an organic solvent as a pretreatment. . However, since the organic solvent used for the washing is adsorbed and remains on the surface of the metal particles, it is highly likely that the adsorption of the binder resin is inhibited and the same thing as the invention described in JP-A-10-254150 occurs. Also in the invention described in JP-A-8-166678, the addition of the resin is divided into two stages, and the solid content of the coating liquid is dispersed in a state higher than the final concentration. Similarly, JP-A-10-254150 and JP-A-10-254150. 2000-
Although less than the invention described in Japanese Patent No. 112164, a phenomenon occurs that inhibits the adsorption of the binder resin.

[0014]

The problem to be solved by the present invention is to form a uniform undercoat layer having good dispersibility, excellent stability over time as a coating liquid, and excellent coatability on a conductive substrate. PROBLEM TO BE SOLVED: To provide a formable undercoat coating liquid for an electrophotographic photosensitive member and a method for producing the same, and to provide an electrophotographic photosensitive member obtained by applying the undercoat layer coating liquid for an electrophotographic photosensitive member. Another object of the present invention is to provide an image forming apparatus.

[0015]

As a result of intensive studies to solve the above problems, the present inventor has found that at least a metal oxide and a binder resin are dispersed in an undercoat layer coating for an electrophotographic photoreceptor. To disperse the working fluid, two or more kinds of ketone solvents are added from the initial stage of the dispersion process, and the metal oxide is wet pulverized to prevent the non-dispersion from disappearing and prevent the generation and increase of aggregates over time. The inventors have discovered what is possible and have completed the present invention based on this finding.

According to the present invention, the following (1) to (7) are provided. (1) In a method for producing an electrophotographic photoreceptor undercoat layer coating liquid in which at least metal oxide particles and a binder resin are dispersed,
An undercoat layer coating for an electrophotographic photosensitive member, characterized in that a mixed solvent of a cyclic ketone solvent and a side chain ketone solvent that dissolves the binder resin is added from the initial stage of the dispersion step, and the metal oxide is wet pulverized. Manufacturing method of working fluid. (2) The method for producing a coating liquid for undercoat layer for electrophotographic photoreceptor according to (1), wherein the solid content of the metal oxide is 50 wt% or less when wet-milled. (3) The method for producing a coating liquid for undercoat layer for electrophotographic photoreceptor according to (1) or (2) above, wherein titanium oxide or a surface-treated titanium oxide is used as the metal oxide. (4) The method for producing a coating liquid for undercoat layer for electrophotographic photoreceptor according to any one of (1) to (3) above, wherein a mixed solvent of methyl ethyl ketone and cyclohexane is used as the mixed solvent.

(5) An undercoat layer coating solution for electrophotography, which is obtained by the method according to any one of (1) to (4) above.

(6) An electrophotographic photoreceptor having a photosensitive layer on a conductive substrate via an undercoat layer, the undercoat layer being formed by applying the undercoat layer coating solution according to (5) above. An electrophotographic photoconductor characterized by being formed as follows.

(7) An image forming apparatus comprising the electrophotographic photosensitive member described in (6) above.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An undercoat layer coating solution for an electrophotographic photoreceptor of the present invention, a method for producing the same, an electrophotographic photoreceptor coated with the undercoat layer coating solution, and the same are provided below. The image forming apparatus to be used will be described in detail.

As a ketone solvent for dispersing the coating liquid for undercoat layer for electrophotographic photoreceptor of the present invention, acetone, methylacetone, methylethylketone, methyl-n-butylketone, methylisobutylketone, methyl-n-amylketone, Side chain ketones such as methyl-n-hexyl ketone, diethyl ketone, ethyl-n-butyl ketone, di-n-propyl ketone, diisobutyl ketone, acetonylacetone, diacetone alcohol, mesityl oxide and cyclohexanone, methylcyclohexane, holone, Cyclic ketones such as isophorone can be used. Particularly, the ketone solvent to be mixed is preferably a mixture of a side chain ketone and a cyclic ketone. Furthermore, it is desirable to mix methyl ethyl ketone and cyclohexanone.

It is not clear why the mixed solvent has improved dispersibility when two or more of the above-mentioned ketone solvents are mixed, but dispersion in a mixed solvent system of a side chain ketone and a cyclic ketone is more preferable. Since it is excellent in nature, it does not have as strong a hydrogen-bonding property as a hydroxyl group, but it has the ability to adsorb to the surface of titanium oxide due to the presence of a carboxyl group, and due to side chain ketones and cyclic ketones with slightly different polarities and solubility parameters. It is imagined that the interaction between the solvents is caused.

The mixing weight ratio of the two ketone solvents is 3 /
7 to 7/3 is recommended. When one of the ketone-based solvents is 30 wt% or less of the whole, the effect similar to that of the single ketone-based solvent or the dispersibility is weak.

The metal oxide used in the coating liquid for undercoat layer for electrophotographic photoreceptor of the present invention includes titanium oxide, zinc oxide, lead white, aluminum oxide, aluminum oxide, silicon oxide, indium oxide, zirconium oxide, Examples thereof include magnesium oxide and the like. Among them, titanium oxide and surface-treated titanium oxide (for example, titanium oxide surface-treated with alumina, zirconia, silica, siloxane, stearic acid, etc.) are preferably used.

The titanium oxide particles used in the present invention have a large refractive index as compared with other white pigments, are physically and chemically stable, and have excellent hiding power and whiteness. It is used in various other fields, and there are two types of crystal type, rutile type and anatase type, and both can be used, but in the present invention, the rutile type is preferably used. Further, those whose surface is surface-treated with a hydrous oxide such as aluminum or silicon, or stearic acid can be preferably used.

The metal oxide particles of the present invention and the above-mentioned two or more kinds of ketone solvents are used in a ball mill, a vertical sand mill,
Horizontal sand mill, dispersed in the binder by a crushing type dispersing machine using a dispersion medium such as a paint conditioner, for example ultrasonic dispersion method without using the dispersion medium,
Roll mills, impact mills, etc. are not used.

Examples of the material of the dispersion medium used for the wet pulverization of the coating liquid for the undercoat layer of the present invention include alumina, zirconia, titania, PSZ and YTZ. The dispersion medium has a function of being thrown into the above-mentioned disperser together with the metal oxide particles, applying a strong force to the metal oxide to pulverize the metal oxide, and dispersing the metal oxide in the binder. The shape is a bead shape with a diameter of several mm, a ball shape with a diameter of several mm to several cm,
Alternatively, various materials such as a cylindrical shape can be used.

The binder resin used in the coating liquid for the undercoat layer is styrene, vinyl acetate, acrylic ester,
Polymers and copolymers of vinyl compounds such as methacrylic acid esters, silicone resins, phenoxy resins, polysulfone resins, polyvinyl butyral resins, polyvinyl formal resins, polyester resins, cellulose ester resins, cellulose ether resins, urethane resins, phenolic resins, epoxies Examples thereof include resins, polycarbonate resins, polyarylate resins, polyamide resins, polyimide resins, melamine resins and alkyd resins.

The ratio of the metal oxide particles to the binder resin in the present invention is 100 parts by weight of the metal oxide particles.
The binder resin is used in the range of 1 to 1000 parts by weight, preferably 1 to 100 parts by weight. Metal oxide particles /
When the binder resin is 100/1 or less, the chargeability of the photoconductor is deteriorated, and when an image is formed by an image forming apparatus equipped with the photoconductor, the background is markedly soiled. Further, when the metal oxide / binder resin is 100/100 or more, the sensitivity of the photosensitive member deteriorates after continuous use, and when an image is formed by an image forming apparatus equipped with the photosensitive member, a remarkable decrease in density of black portions occurs. To do.

Regarding the method for producing the coating liquid for the undercoat layer of the present invention, a metal oxide, a ketone solvent,
A binder resin is added and dispersion is carried out for a desired time. The above-mentioned ratio is optimum as the ratio of the metal oxide and the binder resin, but the solid content concentration relative to the total liquid amount at the time of dispersion is 5% of the total liquid amount.
0 wt% or less is desirable. Although the reason for this is not clear, when the amount of the metal oxide and the binder resin increases as a whole, the amount of primary particles generated as the metal oxide increases,
Since the binder resin approaches a saturated state with respect to the solubility in a solvent, there is a high risk of causing a recrystallization phenomenon of the binder resin or reaggregation of primary particles due to pressure or temperature. Therefore, the dispersion stability of the coating liquid for the undercoat layer is lowered, or a large amount of undispersed material is generated immediately after the dispersion.

FIG. 1 is a cross-sectional view showing one example of the constitution of an electrophotographic photosensitive member using the coating liquid for the undercoat layer of the present invention. The electrophotography shown in the present invention on a conductive support 1. The undercoat layer 2 formed by applying the undercoat layer coating liquid for a photoreceptor and the photosensitive layer 3 are laminated. FIG. 2 is a sectional view showing another constitutional example of the electrophotographic photosensitive member of the present invention, in which at least an undercoat layer 2 is provided on a conductive support 1 and a charge generation layer 4, a charge as a constitution of a function separation type photosensitive member. The example which laminated the transport layer 5 is shown.

The electrophotographic photosensitive member having the function-separated structure shown in FIGS. 1 and 2 will be described below. The conductive support 1 has a volume resistance of 10 ¹⁰ Ω · cm or less, for example,
Aluminum, nickel, chrome, nichrome, copper, gold,
Metals such as silver and platinum, metal oxides such as tin oxide and indium oxide, coated on film or cylindrical plastic or paper by vapor deposition or sputtering, or aluminum, aluminum alloy, nickel, stainless steel, etc. Extruding boards and them,
It is possible to use a tube that has been surface-treated by cutting, superfinishing, polishing, etc. after forming it into a raw tube by a method such as drawing. Further, the endless nickel belt and the endless stainless belt disclosed in JP-A-52-36016 can also be used as the conductive support 1.

Besides, the conductive support 1 of the present invention may be formed by coating the support with conductive powder dispersed in a suitable binder resin. Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide such as conductive titanium oxide, conductive tin oxide and ITO. Examples include powder. Further, the binder resin used at the same time, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate,
Cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin,
Examples thereof include thermoplastic, thermosetting resins and photocurable resins such as silicone resins, epoxy resins, melamine resins, urethane resins, phenol resins and alkyd resins. Such a conductive layer can be provided by dispersing these conductive powders and a binder resin in a suitable solvent, for example, tetrahydrofuran, dichloromethane, 2-butanone, toluene or the like and applying the dispersion.

Further, a heat-shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber or fluororesin on a suitable cylindrical substrate is electrically conductive. Those provided with a conductive layer can also be favorably used as the conductive support 1 of the present invention.

The undercoat layer 2 produced using the undercoat layer coating liquid for an electrophotographic photoreceptor of the present invention is as described above. Explaining in more detail, the undercoat layer 2 of the present invention will be described below. The ratio P / R of the contained metal oxide particles (P) to the binder resin (R) is preferably in the range of 0.9 / 1 to 2/1 in terms of volume ratio. When the P / R ratio of the undercoat layer is less than 0.9 / 1, the properties of the undercoat layer depend on the properties of the binder resin,
In particular, the characteristics of the photoconductor greatly change due to changes in temperature and humidity and repeated use. Further, when the P / R ratio exceeds 2/1, the number of voids in the undercoat layer increases, the adhesiveness with the charge generation layer decreases, and when it exceeds 3/1, air accumulates. This causes bubbles during coating and drying of the photosensitive layer, resulting in coating defects. A suitable film thickness of the undercoat layer 2 is 0.1 to 10 μm.

The coating solution for the undercoat layer or the photosensitive layer for the electrophotographic photoreceptor of the present invention may be a dip coating method, spray coating, bead coating, nozzle coating, spinner coating, ring coating, Mayer bar coating, or roller. A method such as coating or curtain coating can be used. Particularly in spray coating, it is useful because the coating liquid directly forms a coating film due to the aggregation of liquid and the presence of undispersed substances. FIG. 3 is a view of a conventional spray coating device, in which the conductive cylindrical substrate 3 is clamped on the flange 9 (arrow a) and the rotary shaft 6 is rotated to atomize the coating liquid from the tip of the spray nozzle 4. To form a film by spraying on the substrate 3. The spray nozzle 4 moves from the left end to the right end of the base 3 (arrow b).

In the function-separated type photoreceptor shown in FIG. 2, a photosensitive layer composed of the charge generation layer 4 and the charge transport layer 5 is formed on the undercoat layer.

In the charge generation layer 4, a charge generation substance and a binder resin are dispersed in a suitable solvent by using a ball mill, an attritor, a sand mill, ultrasonic waves, etc., and the resultant is coated on the undercoat layer 2 and dried. Formed by things. A known material can be used for the charge generating substance used in the charge generating layer 4. For example, phthalocyanine-based pigments such as metal phthalocyanine and metal-free phthalocyanine, azurenium salt pigment, squaric acid methine pigment, azo pigment having a carbazole skeleton, azo pigment having a triphenylamine skeleton, azo pigment having a diphenylamine skeleton, dibenzothiophene skeleton Having azo pigment, azo pigment having fluorenone skeleton, azo pigment having oxadiazole skeleton, azo pigment having bisstilbene skeleton, azo pigment having distyryl oxadiazole skeleton, azo pigment having distyryl carbazole skeleton, perylene Series pigments, anthraquinone series or polycyclic quinone series pigments, quinone imine series pigments, diphenylmethane and triphenylmethane series pigments, benzoquinone and naphthoquinone series pigments, cyanine and azomethine series pigments, Jigoido based pigments, and bisbenzimidazole pigments. These charge generating substances can be used alone or as a mixture of two or more kinds.

As the binder resin used in the charge generation layer 4, butyral resin, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl formal, polyvinyl ketone, polystyrene, poly-vinylcarbazole,
Polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyvinyl pyridine, cellulosic resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, etc. are used alone or in combination. To be Above all, it is preferable to use butyral resin, and it is also preferable to use 50% by weight or more of butyral resin and 50% by weight or less of other resin in combination. The amount of the binder resin is 10 to 500 parts by weight, preferably 25 to 300 parts by weight, based on 100 parts by weight of the charge generating substance.

As the solvent used here, isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin, etc. Can be given. The thickness of the charge generation layer is 0.01 to 5 μm, preferably 0.1 to 2 μm.

On the other hand, the charge transport layer 5 can be formed by dissolving or dispersing the charge transport substance and the binder resin in a suitable solvent, coating the resultant on the charge generating layer, and drying. Examples of the solvent used here include chloroborm, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, dichloromethane, cyclohexanone, methyl ethyl ketone, acetone and the like.

The charge transport material contained in the charge transport layer 5 includes a hole transport material and an electron transport material. Examples of the electron transport material include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,
4,7-trinitro-9-fluorenone, 2,4,5,
7-tetranitro-9-fluorenone, 2,4,5,7
-Tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-
Examples thereof include electron-accepting substances such as trinitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.

As the hole-transporting substance, poly-N-vinylcarbazole and its derivative, poly-γ-carbazolylethylglutamate and its derivative, pyrene-formaldehyde condensate and its derivative, polyvinylpyrene, polyvinylphenanthrene, polysilane, Oxazole derivative, oxadiazole derivative, imidazole derivative, monoarylamine derivative, diarylamine derivative, triarylamine derivative, stilbene derivative,
α-phenylstilbene derivative, benzidine derivative, diarylmethane derivative, triarylmethane derivative, 9
-Styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, and other known materials such as polymerized hole transport substances can be mentioned. Examples of the binder resin used in the charge transport layer include polystyrene and styrene-
Acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate, phenoxy resin, Polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin, JP-A-5- 15825
Examples thereof include thermoplastic or thermosetting resins such as various polycarbonate copolymers described in JP-A-0 / JP-A-6-51544.

The amount of the charge transport substance is 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin.
Parts by weight are suitable. The thickness of the charge transport layer is 5 to 5
It is preferably about 0 μm.

In the present invention, a plasticizer, a leveling agent, an antioxidant, etc. may be added to the charge transport layer 6 if necessary. As the plasticizer, general-purpose plasticizers for resins such as dibutyl phthalate and dioctyl phthalate can be used, and the amount thereof is suitably 0 to 30 parts by weight with respect to 100 parts by weight of the binder resin. As a leveling agent,
Silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain can be used, and the amount thereof is 0 based on 100 parts by weight of the binder resin.
-1 part by weight is suitable. As the antioxidant, hindered phenol compounds, sulfur compounds, phosphorus compounds,
Antioxidants such as hindered amine compounds, pyridine derivatives, piperidine derivatives, and morpholine derivatives can be used, and the amount thereof is 0-5 with respect to 100 parts by weight of the binder resin.
About parts by weight is suitable.

Next, the case where the photosensitive layer has a single layer structure (FIG. 1) will be described. When a single-layer photosensitive layer is provided by the casting method, it can be formed by dissolving or dispersing a charge generating substance, a low molecular weight compound and a high molecular weight charge transporting substance in a suitable solvent, and coating and drying the solution. The above-mentioned materials can be used for the charge generating substance and the charge transporting substance.

If desired, a plasticizer may be added to the single-layer photosensitive layer. Further, as the binder resin that can be used as necessary, the binder resin described above in the charge transport layer may be used as it is, or the binder resin described in the charge generation layer 31 may be mixed and used. The thickness of the single-layer photosensitive layer is appropriately about 5 to 100 μm, preferably about 10 to 22 μm.

In the photoreceptor of the present invention, a protective layer (not shown) may be provided for the purpose of improving the durability of the photoreceptor. The materials used for this are ABS resin, ACS
Resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallyl sulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyether sulfone, polyethylene, polyethylene Examples thereof include terephthalate, polyimide, acrylic resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride and epoxy resin.

As a method for forming the protective layer, a usual coating method can be used. The thickness of the protective layer is 0.1 to 1
0 μm is suitable. In addition to the above, known materials such as aC and a-SiC formed by the vacuum thin film forming method can also be used as the protective layer.

In the photoreceptor of the present invention, it is possible to provide another intermediate layer (not shown) between the photosensitive layer and the protective layer. The another intermediate layer generally uses a resin as a main component. Examples of these resins include polyamide, alcohol-soluble nylon resin, water-soluble butyral resin, polyvinyl butyral, and polyvinyl alcohol. As the method for forming the another intermediate layer, a usual coating method can be used as described above. The film thickness is 0.05 to 2
μm is suitable.

An electrophotographic image forming apparatus equipped with the electrophotographic photosensitive member of the present invention will be described. As shown in FIG. 4, a charging member is provided on the outer peripheral surface of a drum-shaped electrophotographic photosensitive member 12 rotating in the direction of arrow A. 1, the photoconductor 12 is charged to a predetermined positive or negative voltage. A positive or negative DC voltage is applied to the charging member 1. The DC voltage applied to the charging member 1 is preferably -2000V to + 2000V.

In addition to the DC voltage, an AC voltage may be superimposed on the charging member 1 to apply a pulsating voltage. The AC voltage superimposed on the DC voltage is the peak-to-peak voltage 40
A voltage of 00 V or less is preferable. However, when the AC voltage is superposed, the charging member and the electrophotographic photosensitive member may vibrate and generate an abnormal sound. A desired voltage may be instantly applied to the charging member 1, but the applied voltage may be gradually increased in order to protect the photoconductor.

In addition to the charging method in which the charging member is indirectly arranged, that is, the so-called scorotron method or corotron method, a charging method in which the charging member is directly arranged on the photoconductor capable of suppressing the generation of acid gas has been proposed. The charging member 1 is the photoconductor 12
It may be rotated in the same direction or in the opposite direction, or may be slid on the outer peripheral surface of the photoconductor without being rotated. Further, the charging member may have a function of cleaning the residual toner on the photoconductor 12. In this case, it is not necessary to provide the cleaning means 10.

The charged photoconductor 12 is then subjected to optical image exposure 6 (slit exposure, laser beam scanning exposure, etc.) by image exposure means (not shown). During this exposure scanning, the exposure is interrupted for the non-image area on the current surface, and the image area that has become a low potential due to the exposure is subjected to reversal development by applying a development bias slightly lower than the surface potential. An electrostatic latent image corresponding to the original image is sequentially formed including the non-image portion.

The electrostatic latent image is then toner-developed by the developing means 7, and the toner-developed image is transferred by the transfer charging means 8 from the paper feeding portion (not shown) to the space between the photoconductor 12 and the transfer member 8. Is sequentially transferred to the surface of the recording material 9 fed in synchronization with the rotation of the recording material. The recording material 9 having undergone the image transfer is separated from the surface of the photoconductor and introduced into an image fixing means (not shown) to be subjected to the image fixing and printed out as a copy. The surface of the photoconductor 12 after the image transfer is subjected to removal of the transfer residual toner by the cleaning unit 10 to have a normal surface, and is subjected to charge removal processing by the pre-exposure 11 and repeatedly used for image formation.

The electrophotographic apparatus is constructed by integrally combining a plurality of constituent elements such as the above-mentioned photosensitive member and developing means as an apparatus unit, and this unit is detachably attached to the apparatus main body. May be. For example, as shown in FIG. 5, at least the photoconductor 12, the charging member 1 and the developing means 7 are housed in a container 20 to form one electrophotographic apparatus unit, and this apparatus unit is used by using a guide means such as a rail of the apparatus body. It may be detachable. The cleaning means 10 may or may not be provided inside the container 20.
Further, as shown in FIG. 6, at least the photoconductor 12 and the charging member 1 are housed in the first container 21 to form a first electrophotographic unit, and at least the developing means 7 is housed in the second container 22. The electrophotographic unit may be used, and the first device unit and the second device unit may be detachable. The cleaning means 10 may or may not be provided in the container 21. 5 and 6, the transfer member 23 is used as the transfer charging means. The transfer member 23 may have the same structure as the charging member 1. The transfer member 23 used as the transfer charging means has 400V to 20V.
It is desirable to apply a DC voltage of 00V, and 24 is a fixing means.

[0057]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

(Example 1) High-purity titanium oxide (CREL
Ishihara Sangyo) 100 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content). 60 wt
%): Manufactured by Dainippon Ink and Chemicals, Inc.) A mixture of 25 parts by weight, 42 parts by weight of methyl ethyl ketone, and 18 parts by weight of acetone was charged into a 15 cm glass pot with alumina balls and dispersed for 48 hours, and 14 parts by weight of methyl ethyl ketone for dispensing. , After adding 6 parts by weight of acetone,
After milling for 0.5 hour, the dispersion was discharged to prepare a coating liquid (1) for undercoat layer.

(Example 2) High-purity titanium oxide (CREL
Ishihara Sangyo) 100 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content). 60 wt
%): Manufactured by Dainippon Ink and Chemicals, Inc.) A mixture of 25 parts by weight, 18 parts by weight of methyl ethyl ketone, and 42 parts by weight of methyl isobutyl ketone was charged into a 15 cm glass pot together with an alumina ball and dispersed for 48 hours. After adding 14 parts by weight of methyl isobutyl ketone and milling for 0.5 hour, the dispersion liquid was discharged, and the coating liquid for undercoat layer (2)
Was produced.

(Example 3) High-purity titanium oxide (CREL
Ishihara Sangyo) 100 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content). 60 wt
%): Manufactured by Dainippon Ink and Chemicals, Inc.) A mixture of 25 parts by weight, 42 parts by weight of methyl isobutyl ketone, and 18 parts by weight of cyclohexanone was charged into a 15 cm glass pot with alumina balls and dispersed for 48 hours, and then methyl isobutyl for dispensing. 14 parts by weight of ketone and 6 parts by weight of cyclohexanone were added, milling was carried out for 0.5 hour, and then the dispersion liquid was discharged to prepare a coating liquid (3) for undercoat layer.

Example 4 High-purity titanium oxide (CREL
Ishihara Sangyo) 100 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content). 60 wt
%): Manufactured by Dainippon Ink and Chemicals, Inc.) A mixture of 25 parts by weight, 30 parts by weight of methyl isobutyl ketone, and 30 parts by weight of cyclohexanone was charged into a 15 cm glass pot together with alumina balls and dispersed for 48 hours. After 10 parts by weight of ketone and 10 parts by weight of cyclohexanone were added, milling was carried out for 0.5 hour, and then the dispersion liquid was dispensed to obtain an undercoat layer coating liquid (4).
Was produced.

Example 5 High-purity titanium oxide (CREL
Ishihara Sangyo) 100 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content). 60 wt
%): Manufactured by Dainippon Ink and Chemicals, Inc.) A mixture of 25 parts by weight, methyl isobutyl ketone 18 parts by weight, and cyclohexanone 42 parts by weight was charged in a 15 cm glass pot with alumina balls and dispersed for 48 hours. 6 parts by weight of ketone, 1 cyclohexanone
After adding 4 parts by weight, milling was carried out for 0.5 hour, and then the dispersion liquid was discharged to prepare an undercoat layer coating liquid (5).

Example 6 High-purity titanium oxide (CREL
Ishihara Sangyo) 100 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content). 60 wt
%): Manufactured by Dainippon Ink & Chemicals, Inc.) A mixture of 25 parts by weight, 42 parts by weight of methyl ethyl ketone, and 18 parts by weight of cyclohexanone was charged into a 15 cm glass pot with alumina balls and dispersed for 48 hours, and then methyl ethyl ketone for dispensing. After 14 parts by weight and 6 parts by weight of cyclohexanone were added, milling was carried out for 0.5 hour, and then the dispersion liquid was discharged to prepare a coating liquid (6) for undercoat layer.

Example 7 High-purity titanium oxide (CREL
Ishihara Sangyo) 100 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content). 60 wt
%): Manufactured by Dainippon Ink and Chemicals, Inc.) A mixture of 25 parts by weight, 30 parts by weight of methyl ethyl ketone and 30 parts by weight of cyclohexanone was charged into a 15 cm glass pot together with balls made of alumina and dispersed for 48 hours. After adding 10 parts by weight and 10 parts by weight of cyclohexanone, milling was carried out for 0.5 hour, and then the dispersion liquid was discharged to prepare an undercoat layer coating liquid (7).

Example 8 High-purity titanium oxide (CREL
Ishihara Sangyo) 100 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content). 60 wt
%): Manufactured by Dainippon Ink and Chemicals, Inc.) A mixture of 25 parts by weight, 18 parts by weight of methyl ethyl ketone, and 42 parts by weight of cyclohexanone was charged into a 15 cm glass pot with alumina balls and dispersed for 48 hours, and then methyl ethyl ketone for dispensing. After 6 parts by weight and 14 parts by weight of cyclohexanone were added, milling was carried out for 0.5 hour, and then the dispersion liquid was discharged to prepare a coating liquid (8) for the undercoat layer.

(Example 9) Surface treatment titanium oxide (titanium oxide surface treated with alumina or zirconia: CR
97 Ishihara Sangyo Co., Ltd.) 45 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%):
25 parts by weight of Dainippon Ink and Chemicals, melamine resin (Super Beckamine L-121-60 (solid content 60w
t%): manufactured by Dainippon Ink and Chemicals, Inc.) A mixture of 15 parts by weight, 42 parts by weight of methyl ethyl ketone, and 18 parts by weight of acetone is charged into a 15 cm glass pot together with alumina balls and dispersed for 48 hours. A layer coating liquid (9) was prepared.

(Example 10) Surface-treated titanium oxide (CR
97 Ishihara Sangyo Co., Ltd.) 45 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%):
25 parts by weight of Dainippon Ink and Chemicals, melamine resin (Super Beckamine L-121-60 (solid content 60w
t%): manufactured by Dainippon Ink and Chemicals, Inc.) 15 parts by weight, methyl ethyl ketone 18 parts by weight, methyl isobutyl ketone 42
A mixture consisting of parts by weight was charged in a 15 cm glass pot together with alumina balls and dispersed for 48 hours, and the liquid was discharged to prepare a coating liquid (10) for undercoat layer.

Example 11 Surface-treated titanium oxide (CR
97 Ishihara Sangyo Co., Ltd.) 45 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%):
25 parts by weight of Dainippon Ink and Chemicals, melamine resin (Super Beckamine L-121-60 (solid content 60w
t%): manufactured by Dainippon Ink and Chemicals, Inc.) A mixture consisting of 15 parts by weight, 42 parts by weight of methyl isobutyl ketone, and 18 parts by weight of cyclohexanone was charged into a 15 cm glass pot together with balls made of alumina for 48 hours, and the liquid was dispensed. An undercoat layer coating liquid (11) was prepared.

(Example 12) Surface-treated titanium oxide (CR
97 Ishihara Sangyo Co., Ltd.) 45 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%):
25 parts by weight of Dainippon Ink and Chemicals, melamine resin (Super Beckamine L-121-60 (solid content 60w
t%): manufactured by Dainippon Ink and Chemicals, Inc.) A mixture of 15 parts by weight, 30 parts by weight of methyl isobutyl ketone, and 30 parts by weight of cyclohexanone is charged into a 15 cm glass pot together with an alumina ball and dispersed for 48 hours, and the liquid is discharged. An undercoat layer coating liquid (12) was prepared.

(Example 13) Surface-treated titanium oxide (CR
97 Ishihara Sangyo Co., Ltd.) 45 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%):
25 parts by weight of Dainippon Ink and Chemicals, melamine resin (Super Beckamine L-121-60 (solid content 60w
t%): manufactured by Dainippon Ink & Chemicals, Inc.) A mixture of 15 parts by weight, 18 parts by weight of methyl isobutyl ketone, and 42 parts by weight of cyclohexanone is charged into a 15 cm glass pot with alumina balls and dispersed for 48 hours, and the liquid is discharged. An undercoat layer coating liquid (13) was prepared.

Example 14 Surface-treated titanium oxide (CR
97 Ishihara Sangyo 100 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt
%): 50 parts by weight of Dainippon Ink and Chemicals, melamine resin (Super Beckamine L-121-60 (solid content 6)
(0 wt%): manufactured by Dainippon Ink and Chemicals, Inc.) A mixture of 25 parts by weight, 42 parts by weight of methyl ethyl ketone, and 18 parts by weight of cyclohexanone was charged in a 15 cm glass pot together with alumina balls for 48 hours, and the solution was dispensed and subbing. A layer coating liquid (14) was prepared.

(Example 15) Surface-treated titanium oxide (CR
97 Ishihara Sangyo) 100 parts, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content). 60 wt
%): Manufactured by Dainippon Ink and Chemicals, Inc.) A mixture of 25 parts by weight, 30 parts by weight of methyl ethyl ketone, and 30 parts by weight of cyclohexanone was charged into a 15 cm glass pot with alumina balls and dispersed for 48 hours, and the dispersion liquid was discharged.
An undercoat layer coating liquid (15) was prepared.

(Example 16) Surface-treated titanium oxide (CR
97 Ishihara Sangyo 100 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt
%): 50 parts by weight of Dainippon Ink and Chemicals, melamine resin (Super Beckamine L-121-60 (solid content 6)
(0 wt%): manufactured by Dainippon Ink and Chemicals, Inc.) A mixture of 25 parts by weight, 18 parts by weight of methyl ethyl ketone, and 42 parts by weight of cyclohexanone was charged in a 15 cm glass pot together with an alumina ball for 48 hours, and the solution was dispensed and the subbing was performed. A layer coating liquid (16) was prepared.

Comparative Example 1 An undercoat layer coating solution (17) was prepared in the same manner as in Example 1 except that the amount of methyl ethyl ketone was changed to 42 parts by weight and the amount of acetone was changed from 18 parts by weight to 60 parts by weight of methyl ethyl ketone. ) Was produced.

(Comparative Example 2) A coating solution for an undercoat layer was prepared in the same manner as in Example 1 except that 42 parts by weight of methyl ethyl ketone and 60 parts by weight of methyl isobutyl ketone were used instead of 18 parts by weight of acetone. (18) was produced.

Comparative Example 3 An undercoat layer coating solution (19) was prepared in the same manner as in Example 1, except that 42 parts by weight of methyl ethyl ketone and 60 parts by weight of cyclohexanone were used instead of 18 parts by weight of acetone. ) Was produced.

Comparative Example 4 A coating solution for undercoat layer (20) was prepared in the same manner as in Example 1 except that 60 parts by weight of tetrahydrofuran was used instead of 42 parts by weight of methyl ethyl ketone and 18 parts by weight of acetone. ) Was produced.

Coating liquids (1) to
In (20), when the liquid was discharged from the glass pot, the whole liquid was filtered with a stainless steel metal mesh (# 1400), and the undispersed material remaining in the mesh was observed. The "payout" referred to here means the following. In the present invention, the undercoat layer coating liquid is a pigment dispersion type coating liquid, and ball mill dispersion is performed to disperse titanium oxide. It is said that paying out only the liquid after the dispersion is completed. In detail, if you normally open the lid and tilt the glass pot to try to get the liquid into the container, the balls will of course pop out together, so the lid should be opened with a gap so that the ball does not come out. In addition, the generation of aggregates over time was sampled immediately after filtering 50 g of the whole liquid, 3 days, 7 days, and 14 days after filtration, and filtered through a stainless steel metal mesh to observe the aggregates remaining on the mesh. did. The results are shown in Table 1.

[0079]

[Table 1] Evaluation criteria immediately after the completion of the secondary milling ⊚: There is no undispersed substance ○: There are 10 or more undispersed substances visually: Δ: 10 to 100 undispersed substances visually ×: Stainless steel mesh It causes root blockage and undispersed material is collected on the entire surface. Evaluation criteria after filtering all liquids ⊚: No agglomerates ○: There are 5 or less agglomerates visually, Δ: 5 to 30 undispersed grains visually ×: Stainless mesh is blocked Agglomerates are collected on the entire surface.

From Table 1, two types of ketone solvents, especially those subjected to primary milling with a side chain ketone solvent and a cyclic ketone solvent are excellent in the amount of undispersed substances and the generation of aggregates over time. This is remarkable in the combination of cyclohexanone. Furthermore, it can be seen that it is particularly remarkable when the solid content concentration in the primary milling is 50 wt% or less. However, in the comparative examples, it can be seen that undispersed substances are generated and aggregates are generated with the passage of time when the substances are dispersed using a single solvent.

(Examples 17 to 32, Comparative Examples 5 to 8) Electrophotographic photoreceptors were prepared by dip coating under the following conditions.

(Undercoat layer coating liquid) The undercoat layer coating liquids (1) to (20) were used.

(Preparation of Coating Liquid for Charge Generation Layer) Dispersion in a ball mill for 240 hours in 25 parts by weight of a disazo pigment represented by the following structural formula (1), 25 parts by weight of τ type metal-free phthalocyanine, and 300 parts by weight of cyclohexanone. I went. After dispersion, polyvinyl butyral (S-REC BX-1:
Sekisui Chemical Co., Ltd. (manufactured) 4 parts by weight of methyl ethyl ketone 3
A resin liquid dissolved in 00 parts by weight and 1680 parts by weight of cyclohexanone was added and dispersed for 3 hours to prepare a coating liquid for charge generation layer.

[Chemical 1]

(Preparation of coating liquid for charge transport layer) 8 parts by weight of a charge transport material represented by the following structural formula (2), 10 parts by weight of polycarbonate (Z type: viscosity average molecular weight 50,000), silicone oil (KF- 50: manufactured by Shin-Etsu Chemical Co., Ltd.)
002 parts by weight was dissolved in 100 parts by weight of tetrahydrofuran to prepare a charge transport layer coating liquid.

[Chemical 2]

On a φ30 × 340 mm aluminum drum, the undercoat layer coating solution described above was applied by dip coating.
It was dried at 0 ° C. for 20 minutes to prepare an intermediate layer having a film thickness of 4 μm. Next, a charge generating layer and a charge transporting layer were successively applied by dip coating on this to obtain an electrophotographic photoreceptor. The charge generation layer is 0.2
μm and the charge transport layer were applied at a coating speed such that the thickness became 30 μm, and each was dried at 130 ° C. for 30 minutes.

The state of the coating film of the electrophotographic photosensitive member thus obtained was visually inspected, and a copy machine Imagio MF65 manufactured by Ricoh Co., Ltd. was used.
It was mounted on 50 and image evaluation was carried out at trim, all black, and halftone density. The results are shown in Table 2.

[0087]

[Table 2] Evaluation Criteria for Appearance of Photoreceptor ◎: No defect ○: Black spots of φ0.2 mm or less △: Many black spots of φ0.2 mm or less ×: Black spots of φ0.2 mm or more

From Table 2, Examples 17 to 32 show the results of image evaluation by the electrophotographic photosensitive member prepared by using the coating liquid for undercoat layer of the present invention and the image forming apparatus equipped with the same. In the example, there is no particular problem, but in the comparative example, an undispersed material generated at the time of dispersion of the coating liquid for the undercoat layer or an agglomerate generated after the dispersion is present in the coating film, therefore, at the time of coating the charge generation layer. It can be seen that the charge-generating substance aggregates and appears as black spots, which also affects the image.

(Example 33) (Preparation of coating liquid for undercoat layer) High-purity titanium oxide (CRE)
L Ishihara Sangyo) 100 parts by weight, alkyd resin (Beckolite M6401-50-S (solid content 50 wt%):
50 parts by weight of Dainippon Ink and Chemicals, melamine resin (Super Beckamine L-121-60 (solid content 60w
t%): manufactured by Dainippon Ink and Chemicals, Inc.) A mixture of 25 parts by weight, 42 parts by weight of methyl isobutyl ketone, and 18 parts by weight of cyclohexanone was charged in a 15 cm glass pot together with an alumina ball and dispersed for 48 hours. After adding 14 parts by weight of isobutyl ketone and 6 parts by weight of cyclohexanone, after milling for 0.5 hour, the liquid was discharged into a container and stirred with a stirrer 213.5 parts by weight of methyl isobutyl ketone and 91.5 parts by weight of cyclohexanone. Part was dropped to prepare an undercoat layer coating liquid (21).

(Preparation of Coating Liquid for Charge Generation Layer) Next, 25 parts by weight of the disazo pigment of the structural formula (1), 25 parts by weight of τ type metal-free phthalocyanine, and 300 parts by weight of cyclohexanone were dispersed in a ball mill for 240 hours. I went. After the dispersion was completed, 4 parts by weight of polyvinyl butyral (S-REC BX-1: Sekisui Chemical Co., Ltd.) was added to methyl ethyl ketone 270.
A resin liquid dissolved in 0 parts by weight and 2400 parts by weight of cyclohexanone was added and dispersed for 3 hours to prepare a coating liquid for charge generation layer.

(Preparation of Coating Liquid for Charge Transport Layer) 8 parts by weight of the charge transport material represented by the structural formula (2), 10 parts by weight of polycarbonate (Z type: viscosity average molecular weight 50,000), silicone oil (KF- 50: manufactured by Shin-Etsu Chemical Co., Ltd.)
002 parts by weight was dissolved in 100 parts by weight of tetrahydrofuran and 110 parts by weight of cyclohexanone to prepare a coating liquid for charge transport layer.

(Spray coating of electrophotographic photoreceptor) φ10
A 0 × 368 mm aluminum drum was housed in the flange 9 shown in FIG. 3, and the undercoat layer coating solution was spray-coated using the spray coating apparatus shown in FIG. 3 to a dry film thickness of 6 μm. It was dried at 30 ° C. for 30 minutes. After that, the charge generation layer coating liquid is spray-coated to a dry film thickness of 0.2 μm, and the charge transport layer coating liquid is further applied onto the surface of the cylindrical substrate coated with the charge generation layer coating liquid. 25 μm dry film thickness
Spray coating was performed so as to obtain the above, and dried at 150 ° C. for 30 minutes. The state of the coating film of the obtained electrophotographic photosensitive member was visually inspected, and the electrophotographic photosensitive member was mounted on a copying machine Imagio MF6550 manufactured by Ricoh Co., Ltd., and image evaluation was performed in trim, all black, and halftone density. The results are shown in Table 2.

(Example 34) Example 3 was repeated except that the method for preparing the coating liquid for undercoat layer was changed as follows.
An electrophotographic photosensitive member was produced in the same manner as in 3. 100 parts by weight of high-purity titanium oxide (CREL Ishihara Sangyo), 50 parts by weight of alkyd resin (Beckolite M6401-50-S (solid content 50 wt%): Dainippon Ink and Chemicals)
Melamine resin (Super Beckamine L-121-60
(Solid content 60 wt%): manufactured by Dainippon Ink and Chemicals, Inc. 25
Parts by weight, 30 parts by weight of methyl isobutyl ketone, and 30 parts by weight of cyclohexanone were charged into a 15 cm glass pot with alumina balls and dispersed for 48 hours, and 10 parts by weight of methyl isobutyl ketone was dispensed.
After adding 10 parts by weight of cyclohexanone and milling for 0.5 hour, the liquid was discharged into a container, and methyl isobutyl ketone 152. was stirred with a stirrer.
5 parts by weight and 152.5 parts by weight of cyclohexanone were added dropwise to prepare an undercoat layer coating liquid (22).

(Example 35) Example 33 is the same as Example 33 except that the method for preparing the coating liquid for the undercoat layer is changed as follows.
An electrophotographic photosensitive member was produced in the same manner as. 100 parts by weight of high-purity titanium oxide (CREL Ishihara Sangyo), alkyd resin (Beckolite M6401-50-S (solid content 5
0 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content 60 wt%): Dainippon Ink and Chemicals) 25 parts by weight, methyl isobutyl ketone 18 parts by weight. , A mixture of 42 parts by weight of cyclohexanone was charged in a glass pot of 15 cm together with balls made of alumina and dispersed for 48 hours, and 6 parts by weight of methyl isobutyl ketone and 14 parts by weight of cyclohexanone were added, followed by milling for 0.5 hour. After carrying out, the liquid was discharged into a container and stirred with a stirrer 91.5 parts by weight of methyl isobutyl ketone,
213.5 parts by weight of cyclohexanone was added dropwise to prepare an undercoat layer coating liquid (23).

(Example 36) Example 33 is the same as Example 33 except that the method of preparing the coating liquid for the undercoat layer is changed as follows.
An electrophotographic photosensitive member was produced in the same manner as. 100 parts by weight of high-purity titanium oxide (CREL Ishihara Sangyo), alkyd resin (Beckolite M6401-50-S (solid content 5
0 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content 60 wt%): Dainippon Ink and Chemicals) 25 parts by weight, methyl ethyl ketone 42 parts by weight, cyclohexanone A mixture of 18 parts by weight was charged into a 15 cm glass pot together with alumina balls and dispersed for 48 hours, 14 parts by weight of the dispensed methyl ethyl ketone and 6 parts by weight of cyclohexanone were added, and after milling for 0.5 hour, 213.5 parts by weight of methyl ethyl ketone and 91.5 parts by weight of cyclohexanone were added dropwise with stirring with a stirrer to the undercoat layer coating solution (2
4) was produced.

(Example 37) Example 33 is the same as Example 33 except that the method for preparing the coating liquid for the undercoat layer is changed as follows.
An electrophotographic photosensitive member was produced in the same manner as. 100 parts by weight of high-purity titanium oxide (CREL Ishihara Sangyo), alkyd resin (Beckolite M6401-50-S (solid content 5
0 wt%): Dainippon Ink and Chemicals, Inc.) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content 60 wt%): Dainippon Ink and Chemicals, Inc.) 25 parts by weight, methyl ethyl ketone 30 parts by weight, cyclohexanone A mixture consisting of 30 parts by weight was charged into a 15 cm glass pot together with alumina balls and dispersed for 48 hours. After 10 parts by weight of methyl ethyl ketone and 10 parts by weight of cyclohexanone were added, milling was carried out for 0.5 hours. After that, the liquid was discharged into a container, and 152.5 parts by weight of methyl ethyl ketone and 152.5 parts by weight of cyclohexanone were added dropwise with stirring with a stirrer to prepare a coating liquid (25) for undercoat layer.

(Example 38) Example 33 is the same as Example 33 except that the method for preparing the coating liquid for the undercoat layer is changed as follows.
An electrophotographic photosensitive member was produced in the same manner as. 100 parts by weight of high-purity titanium oxide (CREL Ishihara Sangyo), alkyd resin (Beckolite M6401-50-S (solid content 5
0 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content 60 wt%): Dainippon Ink and Chemicals) 25 parts by weight, methyl ethyl ketone 18 parts by weight, cyclohexanone A mixture consisting of 42 parts by weight was charged into a 15 cm glass pot together with alumina balls and dispersed for 48 hours. After 6 parts by weight of methyl ethyl ketone and 14 parts by weight of cyclohexanone were added, milling was carried out for 0.5 hours. After that, the liquid was discharged into a container, and 91.5 parts by weight of methyl ethyl ketone and 213.5 parts by weight of cyclohexanone were added dropwise with stirring with a stirrer to prepare a coating liquid (26) for undercoat layer.

Example 39 Example 33 is the same as Example 33 except that the method for preparing the undercoat layer coating solution is changed as follows.
An electrophotographic photosensitive member was produced in the same manner as. 45 parts by weight of surface treated titanium oxide (CR97 Ishihara Sangyo), alkyd resin (Beckolite M6401-50-S (solid content 5
0 wt%): Dainippon Ink and Chemicals, Inc.) 25 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content 60 wt%): Dainippon Ink and Chemicals, Inc.) 15 parts by weight, methyl isobutyl ketone 42 parts by weight. , 18 parts by weight of cyclohexanone were placed in a 15 cm glass pot with alumina balls and dispersed for 48 hours. The liquid was discharged into a container and stirred with a stirrer 84.7 parts by weight of methyl isobutyl ketone and 3 parts of cyclohexanone.
6.3 parts by weight was added dropwise to prepare an undercoat layer coating liquid (27).

Example 40 Example 33 is the same as Example 33 except that the method for preparing the coating liquid for the undercoat layer is changed as follows.
An electrophotographic photosensitive member was produced in the same manner as. 45 parts by weight of surface treated titanium oxide (CR97 Ishihara Sangyo), alkyd resin (Beckolite M6401-50-S (solid content 5
0 wt%): Dainippon Ink and Chemicals, Inc.) 25 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content 60 wt%): Dainippon Ink and Chemicals, Inc.) 15 parts by weight, methyl isobutyl ketone 30 parts by weight. , A mixture of 30 parts by weight of cyclohexanone and a ball of 15 cm were charged in a glass pot of 15 cm and dispersed for 48 hours, and the liquid was discharged into a container and stirred with a stirrer 60.5 parts by weight of methyl isobutyl ketone and 6 parts of cyclohexanone.
0.5 parts by weight was added dropwise to prepare an undercoat layer coating liquid (28).

(Example 41) Example 33 is the same as Example 33 except that the method for preparing the coating liquid for the undercoat layer is changed as follows.
An electrophotographic photosensitive member was produced in the same manner as. 45 parts by weight of surface treated titanium oxide (CR97 Ishihara Sangyo), alkyd resin (Beckolite M6401-50-S (solid content 5
0 wt%): Dainippon Ink and Chemicals, Inc.) 25 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content 60 wt%): Dainippon Ink and Chemicals, Inc.) 15 parts by weight, methyl isobutyl ketone 18 parts by weight. , 42 parts by weight of cyclohexanone were placed in a 15 cm glass pot together with alumina balls and dispersed for 48 hours. The liquid was discharged into a container and stirred with a stirrer, 36.3 parts by weight of methyl isobutyl ketone and 8 parts of cyclohexanone.
4.7 parts by weight was added dropwise to prepare an undercoat layer coating liquid (29).

(Example 42) Example 33 is the same as Example 33 except that the method for preparing the coating liquid for the undercoat layer is changed as follows.
An electrophotographic photosensitive member was produced in the same manner as. 100 parts by weight of surface treated titanium oxide (CR97 Ishihara Sangyo), 50 parts by weight of alkyd resin (Beckolite M6401-50-S (solid content 50 wt%): Dainippon Ink and Chemicals)
Melamine resin (Super Beckamine L-121-60
(Solid content 60 wt%): manufactured by Dainippon Ink and Chemicals, Inc. 25
Parts by weight, 42 parts by weight of methyl ethyl ketone, and 18 parts by weight of cyclohexanone are charged into a 15 cm glass pot together with alumina balls and dispersed for 48 hours. The liquid is discharged into a container and stirred with a stirrer 84.7 parts by weight of methyl isobutyl ketone. Part, cyclohexanone 3
6.3 parts by weight was added dropwise to prepare an undercoat layer coating liquid (30).

(Example 43) Example 33 is the same as Example 33 except that the method for preparing the coating liquid for the undercoat layer is changed as follows.
An electrophotographic photosensitive member was produced in the same manner as. 100 parts by weight of surface treated titanium oxide (CR97 Ishihara Sangyo), 50 parts by weight of alkyd resin (Beckolite M6401-50-S (solid content 50 wt%): Dainippon Ink and Chemicals)
Melamine resin (Super Beckamine L-121-60
(Solid content 60 wt%): manufactured by Dainippon Ink and Chemicals, Inc. 25
By weight, a mixture of 30 parts by weight of methyl ethyl ketone and 30 parts by weight of cyclohexanone is charged into a 15 cm glass pot with balls made of alumina and dispersed for 48 hours. The liquid is discharged into a container and stirred with a stirrer to give 60.5 parts by weight of methyl isobutyl ketone. Part, cyclohexanone 6
0.5 parts by weight was added dropwise to prepare an undercoat layer coating liquid (31).

(Example 44) An electrophotographic photosensitive member was prepared in the same manner as in Example 33 except that the method for preparing the undercoat layer coating solution in Example 33 was changed as follows. 100 parts by weight of surface treated titanium oxide (CR97 Ishihara Sangyo), alkyd resin (Beckolite M6401-50-S (solid content 5
0 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content 60 wt%): Dainippon Ink and Chemicals) 25 parts by weight, methyl ethyl ketone 18 parts by weight, cyclohexanone A mixture consisting of 42 parts by weight was charged in a 15 cm glass pot with alumina balls and dispersed for 48 hours. The liquid was discharged into a container and stirred with a stirrer, 36.3 parts by weight of methyl isobutyl ketone and 84.7 of cyclohexanone.
Part by weight was dropped to prepare an undercoat layer coating liquid (32).

(Comparative Example 9) An electrophotographic photosensitive member was produced in the same manner as in Example 33, except that the method for producing the undercoat layer coating liquid in Example 33 was changed as follows. 100 parts by weight of high-purity titanium oxide (CREL Ishihara Sangyo), alkyd resin (Beckolite M6401-50-S (solid content 50
wt%): made by Dainippon Ink and Chemicals, Inc.) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content 60 wt%): made by Dainippon Ink and Chemicals, Inc.) 25 parts by weight, and methyl ethyl ketone 60 parts by weight. 1 mixture
Prepared with a ball made of alumina in a 5 cm glass pot and dispersed it for 48 hours.
After adding 1 part by weight, milling was carried out for 0.5 hour, and then the liquid was discharged into a container, 91.5 parts by weight of methyl ethyl ketone and 213.5 parts by weight of cyclohexanone were added dropwise with stirring with a stirrer, and the undercoat layer coating was applied. Working fluid (33)
Was produced.

(Comparative Example 10) Example 33 is the same as Example 33 except that the method for preparing the coating liquid for the undercoat layer is changed as follows.
An electrophotographic photosensitive member was produced in the same manner as. 100 parts by weight of high-purity titanium oxide (CREL Ishihara Sangyo), alkyd resin (Beckolite M6401-50-S (solid content 5
0 wt%): Dainippon Ink and Chemicals, Inc.) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content 60 wt%): Dainippon Ink and Chemicals, Inc.) 25 parts by weight, methyl isobutyl ketone 60 parts by weight. Was mixed with a ball made of alumina in a 15 cm glass pot and dispersed for 48 hours, 20 parts by weight of the discharged methyl isobutyl ketone was added, and after milling for 0.5 hour, the liquid was discharged into a container, While stirring with a stirrer, 91.5 parts by weight of methyl isobutyl ketone and 213.5 parts by weight of cyclohexanone were added dropwise to prepare a coating liquid (34) for undercoat layer.

(Comparative Example 11) Example 33 is the same as Example 33 except that the method of preparing the coating liquid for the undercoat layer is changed as follows.
An electrophotographic photosensitive member was produced in the same manner as. 100 parts by weight of high-purity titanium oxide (CREL Ishihara Sangyo), alkyd resin (Beckolite M6401-50-S (solid content 5
0 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content 60 wt%): Dainippon Ink and Chemicals) 25 parts by weight, cyclohexanone 60 parts by weight Mix 15
cm glass pot with alumina balls 4
After dispersing for 8 hours and adding 20 parts by weight of the dispensed cyclohexanone, after milling for 0.5 hour, the liquid was dispensed into a container, and 213.5 parts by weight of methyl ethyl ketone and 91.5 parts by weight of cyclohexanone while stirring with a stirrer. Part was dropped to prepare an undercoat layer coating liquid (35).

(Comparative Example 12) Example 33 is the same as Example 33 except that the method of preparing the coating liquid for the undercoat layer is changed as follows.
An electrophotographic photosensitive member was produced in the same manner as. 100 parts by weight of high-purity titanium oxide (CREL Ishihara Sangyo), alkyd resin (Beckolite M6401-50-S (solid content 5
0 wt%): Dainippon Ink and Chemicals) 50 parts by weight, melamine resin (Super Beckamine L-121-60 (solid content 60 wt%): Dainippon Ink and Chemicals) 25 parts by weight, tetrahydrofuran 60 parts by weight 1 mixture
Tetrahydrofuran 20 was placed in a 5 cm glass pot and dispersed with alumina balls for 48 hours.
After adding 1 part by weight, milling was carried out for 0.5 hour, and then the liquid was discharged into a container, 213.5 parts by weight of cyclohexanone and 91.5 parts by weight of tetrahydrofuran were added dropwise with stirring with a stirrer, and the undercoat layer coating was applied. Working fluid (36)
Was produced.

The same observations as in Example 1 were carried out on the coating liquid for undercoat layer and the electrophotographic photosensitive member. The results are shown in Table 3.

[Table 3] Evaluation Criteria for Appearance of Photoreceptor ⊚: No Defect ∘: Presence of 1 to 2 Protrusions Δ: Presence of about 10 Protrusions x: Existence of Innumerable Protrusions Since the presence of undispersed materials and agglomerates in the coating is reflected as it is in the coating film, high dispersibility is particularly required, but in the examples, in the image in the photoconductor and the image forming apparatus including the same, In contrast to the fact that almost no problem occurred, in the comparative example, many undispersed substances and agglomerates of the undercoating layer coating liquid caused many protrusions due to the undercoating layer, and in halftone images, the protrusions were There were many black spot images due to white spots and discharge breakdown that occurred in the reservoir where the gap between the two could not be maintained.

[0109]

INDUSTRIAL APPLICABILITY The present invention has good dispersibility, excellent stability over time as a coating liquid, and excellent coatability on a conductive substrate.
A subbing layer coating liquid for an electrophotographic photosensitive member capable of forming a uniform subbing layer is obtained. Further, according to the electrophotographic photosensitive member obtained by applying the coating liquid for the undercoat layer for the electrophotographic photosensitive member and the image forming apparatus equipped with the same, a good quality image can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a layer structure of an electrophotographic photosensitive member of the present invention.

FIG. 2 is a diagram showing a layer structure of another electrophotographic photosensitive member of the present invention.

FIG. 3 is a diagram showing an outline of a spray coating machine.

FIG. 4 is a front view showing an example of an electrophotographic apparatus of the present invention.

FIG. 5 is a front view showing another example of the electrophotographic apparatus of the present invention.

FIG. 6 is a front view showing another example of the electrophotographic apparatus of the present invention.

[Explanation of symbols]

(In FIGS. 1 and 2) 1: Conductive support 2: Undercoat layer 3: Photosensitive layer 4: Charge generation layer 5: Charge transport layer (in FIG. 3) 3 Conductive cylindrical substrate 4 Spray nozzle 6 Rotation axis 9 Flange a Traveling direction of the flange that holds the support holding the conductive cylindrical substrate b Moving direction of the spray nozzle during coating (in FIGS. 4, 5, and 6) 1 Charging member 6 Exposure means 7 Developing means 8 Transfer member (corona type) 9 Recording material 10 Cleaning means 11 Auxiliary power means 12 Photoconductor 20 Container 21 Container 22 Container 23 Transfer member 24 Fixing means

Claims (7)

[Claims] 1. A method for producing a coating liquid for an undercoat layer for an electrophotographic photoreceptor in which at least metal oxide particles and a binder resin are dispersed, and a cyclic ketone solvent and a side which dissolve the binder resin from the beginning of the dispersing step. Add a mixed solvent of chain ketone solvent,
A method for producing a coating liquid for an undercoat layer for an electrophotographic photoreceptor, which comprises wet pulverizing the metal oxide. 2. The method for producing a coating liquid for an undercoat layer for an electrophotographic photosensitive member according to claim 1, wherein a solid content ratio when the metal oxide is wet pulverized is 50 wt% or less. 3. The method for producing an undercoat layer coating liquid for an electrophotographic photoreceptor according to claim 1, wherein titanium oxide or a surface-treated titanium oxide is used as the metal oxide. 4. The method for producing a coating liquid for an undercoat layer for an electrophotographic photosensitive member according to claim 1, wherein a mixed solvent of methyl ethyl ketone and cyclohexane is used as the mixed solvent. 5. An undercoat layer coating liquid for electrophotography, which is obtained by the method according to any one of claims 1 to 4. 6. An electrophotographic photoreceptor having a photosensitive layer on a conductive substrate via an undercoat layer, wherein the undercoat layer is formed by applying the undercoat layer coating solution according to claim 5. An electrophotographic photoconductor characterized by the following. 7. An image forming apparatus comprising the electrophotographic photosensitive member according to claim 6.